Frontotemporal dementia (FTD) is a spectrum of devastating neurodegenerative diseases characterized by progressive impairment in emotional and social behavior, language and executive function. There are no effective treatments at present, although clinical trials are being planned. Some forms of FTD are inherited in an autosomal dominant manner as a result of a mutation in one of several genes that have been identified. In this exploratory proposal, we aim to perform a preliminary investigation of individuals who carry one of these genetic mutations but who are not yet showing symptoms or who are showing questionable or very mild symptoms to try to determine whether MRI measures of brain structure or function or other kinds of biological markers might provide information about changes in the brain that precede symptoms. The ultimate goal of this research is to identify biological markers of the degenerative process of FTD that can be used to measure whether potential future treatments can ameliorate the process prior to the development of symptoms.